Anti-Brexit demonstrators wave an EU flag outside the Houses of Parliament. ‘It is in parliament where the messy, inchoate, often contradictory “will of the people” becomes law. That is the difference between democracy and populism.’ Photograph: Daniel Leal-Olivas/AFP/Getty Images

When a majority of MPs voted a year ago to authorise the activation of article 50, they did so because they felt it was their duty as mandated by the Brexit referendum. But this does not mean parliament has to agree to whatever Brexit Theresa May offers. Democracy demanded that the vote be honoured, but that doesn’t mean everything done under the banner of Brexit is in the interests of the country or an expression of an irreversible “will of the people”. In reality we are dealing with an ever-shifting battleground of political ideas. Democracy means listening to the majority, but it also means managing conflicting ambitions within that majority. Disentangling all the motives that compelled people to tick the leave box is not easy. Neither should the national mood be seen entirely in terms of the winning side, as though remain voters have disappeared and their ideas are not worth considering.

Democracy also means protecting minorities, and 48% is a big minority. A Brexit that would bring the country together is the softest of soft Brexits. But Mrs May decided, without even consulting her cabinet, to go for an extreme model. She sought a mandate for this in a general election and didn’t get one. She pushed ahead regardless, stitching up a pact with the DUP, who don’t even represent the majority vote on Brexit in Northern Ireland, which backed remain. Ireland is a toxic issue. Northern Ireland was torn apart by strife for 30 years until a fragile, precious peace was secured. Any Brexit must uphold the peace process, the Good Friday agreement and therefore the soft border.

A deeply polarised UK

Given the stakes, the government has wantonly squandered half of the time that was available to negotiate a deal. Only a year is now left until the official moment of departure. Last week’s agreement on a transitional phase must not obscure the severity of what will happen next 29 March if the current timetable is pursued. The troubling reality is that outside of the European Union Britain would be worse off in economic terms under every scenario. Brexit threatens the palimpsest of modern Britain on which layer upon layer of a shared European culture has been inscribed. Leaving the EU will not enhance Britain’s place in the world, it will damage it. In an age of aggressive nationalism, when a spirit of contempt for international rules roams the White House, it is hard to see the virtue in withdrawal from a project conceived to protect them.

That is what the referendum vote implies. Yet without sustained evidence that millions of people have had a change of heart, the case for completely reversing the decision is difficult to make at this moment in time. Disappointed remainers must not underestimate the social and political cost of appearing to tell leave voters that their judgment and opinions are invalid; that they were conned, or stupid, or racist. The loss of faith in institutions, ushered in by the 2008 financial crash, stirred resentment against a ruling class. There were previous breaches of trust that created the disillusion with the existing political order: such as Iraq and the fetishising of market forces. The UK has also become deeply polarised, a trend which runs counter to democratic and egalitarian values.

It is important not to lose sight of the ideological genesis of Euroscepticism on the hard right of British politics and society. The path to Brexit required a set of contingencies to occur, but the country set out on this journey when the Tories included an EU referendum pledge in their 2015 manifesto. Many leave voters were Conservatives in well-to-do towns; comfortable baby boomers in southern counties. The extent to which Brexit was a popular revolt by the dispossessed can be overstated, most eagerly by the likes of Boris Johnson and Jacob Rees-Mogg, who would love to have credentials as champions of the underprivileged but don’t deserve them.

Remainers have yet to find a coherent pro-EU offer to those people who voted leave that would demonstrate to them that Europhiles have at long last listened to voices they had ignored for too long. So here is the paradox: Brexit does not fix the underlying problems that led many people to feel that they simply had to reject EU membership to get some kind of redress from a political system in which they had lost confidence. The negative economic consequences of Brexit will be felt hardest in places where the leave vote most looks like a cry for economic help. Blaming the EU (often as a proxy for immigration) was a misdiagnosis of a chronic ailment, which has its roots in Thatcher-era deindustrialisation, a failure to manage the effects of globalisation on wages, and a demand for decent public services. Brexit is the wrong prescription.

Creeping rightwing coup

Withdrawing Brexit has vicious side-effects, not least because referendums have a record of stoking divisions, not healing them. With this in mind, MPs will now have to find a way to leave while mitigating the harm done by leaving. Time is tighter even than the one-year mark suggests. To accommodate the need for continent-wide ratifications, including votes in Westminster, the outline of a deal should be reached by autumn this year. Such a complex project cannot be settled in the next seven months. This is not a question of ambition or imagination but of negotiating capacity.

So the likely outcome is a broad agreement on the approximate shape of a future relationship, with details to be filled in during transition. That is a dangerous situation. It sets up a scenario where the UK leaves the EU on terms that even the Brexiters accept are worse than current membership, and then the government gets to fine-tune the details, with the help of Henry VIII powers that it has awarded itself, and to an agenda dictated by a handful of Tory backbenchers. This is not the restoration of sovereignty or the invigoration of democracy that was promised. It looks more like a creeping rightwing coup. Resisting a course that harms the country is not an offence against democracy. It is a patriotic duty to push back against extreme forces that are exploiting, not honouring, the referendum vote. It is in parliament that society’s competing interests and demands are mediated. It is in parliament where the messy, inchoate, often contradictory “will of the people” becomes law. That is the difference between democracy and populism; between government by stable institutions and mob rule. That is why parliament is sovereign – and it always was, despite the claims of Eurosceptics. Their assertion that Brexit was meant to empower parliament has been exposed as a sleight of hand.

Parliamentary sovereignty

The most egregious displays of contempt for parliamentary sovereignty since the referendum have come not from “Brussels bureaucrats” but from Tory ministers. They even tried to thwart efforts to give MPs a vote on a final deal. Luckily, they failed. Labour were moving in the right direction with their customs partnership proposals and the party needs to resist a hard Brexit at all costs. Neither parliament nor anyone else should be cowed into thinking that the only available deal is the one that Mrs May offers. She has no mandate for the Brexit she seeks. In parliament the majority of pragmatic MPs know this. Yet they lack a credible leader, relying instead on patron saints such as Ken Clarke. Time is running out. Now is the moment to demand a change of course, before it is too late.